Pneumatic dispatch tube apparatus



June 26, 1934.

J. T. NEEDHAM PNEUMATIC DISPATCH TUBE APPARATUS Filed Feb. 16, 1931 3Sheets-Sheet l INVENTOR UOHN T. NEEDHAM ATTORN EYS June 26, 1934. JNEEDHAM 1,964,167

PNEUMATIC DISPATCH TUBE APPARATUS Filed Feb. 1 1931 3 Sheets-Sheet 2INVENTOR \JOH N r. mgaormm ATTORNEYS June 26, 1934. J. T. NEEDHAM1,964,167

PNEUMATIC DISPATCH TUBE APPARATUS Filed Feb. 1931 5 Sheets-Sheet 3 65INVENTOR 4 JOHN T. NEEDHAM ATTORNEYS Patented June 26, I934 NETED gTATESOFFICE John T. Needham, North Plainfield,

N. 5., as-

signor to General Conveyors Limited, Montreal, Quebec, Canada, acorporation of Canada Application February 16, 1931, Serial No. 516,040

36 Claims.

Important objects of the present invention are, to provide an improvedpneumatic dispatch tube apparatus wherein a dispatch tube line isprovided with simple, efficient means for causing a carrier-propellingflow of air in either direction along the tube line to render the line atwo-way dispatch line; to accomplish this purpose by means of oppositelydirected injector devices located at intermediate points in the tubeline; to provide satisfactory means for selectively operating theinjector devices from the terminals of the tube line according to thedirection of carrier transmission; and to provide signal means toindicate at either terminal the approach of a carrier from the otherterminal. Other objects of the invention will appear hereinafter.

In the drawings, Fig. 1 is an elevation of my dispatch tube apparatus,partly in section;

Fig. 2 a fragmentary sectional elevation of a portion of the apparatusshowing a modified means for operating the injector devices;

Fig. 3 a section taken on the line 3-3 of Fig. 2; and

Fig. 4 a view similar to Fig. 1 showing a modified means for supplyingair to the injectors.

The apparatus includes a dispatch tube line I, in the present instancecomprising two end tube sections 2 and 8 and an intermediate tubesection 4. The outer end of tube section 2 has a bell mouth 5 and formsa constantly open terminal. Similarly the outer end of tube section 3 isprovided with a bell mouth 6 and forms a constantly open terminal. Eachof these terminals serves as both a sending terminal and a re- P ceivingterminal. While in the present instance the terminals are formed by theopen tube ends, terminal heads or devices of any suitable form may beemployed. An injector device 7 connects together the tube sections 2 and4 and a similar injector device 8 connects together the sections 3 and4. These devices are oppositely directed longitudinally of the tubeline. They may be located quite close together or spaced far apart alongthe line, according to the requirements of the service.

Each injector device comprises a box-like casing 9 forming an airchamber 10. One of the connected tube sections is screwed into one wallof said casing, as at 11, and said wall is formed with 3 a conical,nozzle-like projection 12 alining with the connected tube sections andformed with a bore 13 forming part of the carrier passage in the tubeline. A threaded aperture 14, alining with nozzle 12, is formed in theopposite wall of the casing and has a threaded sleeve 15 screwed intoit. Said sleeve is formed at its inner end with an annular, conical,internal surface 16 which telescopes over the nozzle 12 and cooperateswith the conical surface of the latter to form an annular injector port17 leading from the chamber 10 obliquely into the tube line. The opposedport-forming surfaces are of material length longitudinally of the tubeline, correspondingly tapered, and their taper makes quite a low anglewith the tube line in order to give positive longitudinal direction tothe air injection. The sleeve receives and rotatably fits an end of oneof the connected tube sections and is formed with a bore forming part ofthe carrier passage. By turning the sleeve the space between thetapering port walls may be varied to change the size of the port and toentirely close the port when required. The port of injector device 7tapers toward the terminal 6 while the port of device 8 tapers towardthe terminal 5.

The injector devices '7 and 8 are supplied with air under pressure froma source indicated at 18, and from said source a pipe 19 leads to pointsopposite the injector devices. A branch pipe 20 leads from pipe 19 tothe chamber 10 of injector device 7 and a branch pipe 21 leads from pipe19 to the chamber of injector device 8. In the form of the inventionshown in Fig. l a valve 22 is connected into branch pipe 20 and a valve23 is connected into branch pipe 21. Fixed to the stem of each valve isa radial operating arm 24. Elec trical means including two solenoids 25and 26 are provided for operating said radial arms and their connectedvalves. In practice said solenoids will be mounted in any suitablemanner in fixed positions. Each solenoid has an elongated core rod 27which has a pin and slot operative connection 28 with one of thevalve-operating arms. When either solenoid is energized by an electriccurrent its rod 27 is drawn inward and the connected valve is rotated tobring its port 29 into position to open communication between the pipe19 and one of the injector devices. When the current is cut off, aspring 30 operates upon the valve arm 24 to rotate the valve to normalposition, 160 closing communication between pipe 19 and the injectordevice and retracting the core rod of the solenoid.

At the terminals 5 and 6 there are switches 31 and 32 respectively forcausing the operation of the solenoids and the operation of signalmeans, to be described hereinafter. Each switch comprises a pair ofnormally separated spring contact fingers 33 and is pivoted as at 34 toswing bodily. One of the spring fingers carries a cam-like insulationprojection which extends inward through an aperture in the dispatch tubeand slightly into the carrier path. A spring 36 yieldably holds theswitch in normal position with a tail portion thereof in contact with astop 37.

When a carrier is inserted into the terminal it strikes the projection35 and flexes the finger which carries the projection to close theswitch. A carrier approaching the terminal for discharge from the tube,however engages said projection and merely rocks the switch out of theway against the spring resistance without closing the switch. When theswitch is released the spring returns it to normal position. A timer,indicated at 38, has a circuit 39 controlled by switch 31. This timercontrols a circuit 40 for the solenoid 25. Another timer 41 has acircuit 42 controlled by switch 32 and in turn controls a circuit 43 forthe solenoid 26. Line wires 44 lead to both timers.

Signal means are provided to indicate to an operator at either end ofthe dispatch line that a carrier has been inserted into the opposite endof the line and thereby warn the operator against the insertion of acarrier. Said signal means includes an electric lamp 45 located near theterminal 5 and an electric lamp 46 located near the terminal 6. Thetimer 41 controls a circuit 47 for the lamp 45 and the timer 38 controlsa circuit 48 for the lamp 46.

The apparatus operates as follows: When a carrier is inserted into theterminal 5, for example, the switch 31 is closed by the carrier and thetimer 38 set into operation. In turn, said timer closes the circuit ofsolenoid 25 and the latter, through its operative connection with valve22, effects the opening of the valve. Thereby air is admitted from pipe19 through branch pipe 29 to the chamber 10 of the injector device 7 andis injected into the tube line toward the terminal 6 with considerableforce and speed through the annular, restricted injector port 17. Theinjection of air into the tube line at an intermediate point betweenterminals 5 and 6 and away from the former causes a suction in the tubesection 2. Thereby the inserted carrier is drawn rapidly inward alongthe line from terminal 5 until it passes the injector port 1'? of theinjector device 7 whereupon it is subjected to the thrust of theinjected air and is propelled rapidly along the tube line to theterminal 6 the switch 32 being rocked out of the way by the carrier.

When a carrier is inserted into the terminal 6 it closes the switch 32and the timer 41 is set into operation. Said timer in turn closes thecircuit of solenoid 26 and the latter through its operative connectionwith valve 23 effects the opening of said valve. Air is thereby admittedfrom pipe 19 through branch pipe 21 to the injector device 8 for thepropulsion of the carrier to the terminal 5 by suction inward fromterminal 6 and by the thrust of the injected air as previouslydescribed. Each timer keeps the valve controlled thereby open for therequired time and then the spring 30 closes the valve to cut off theinjection.

Operation of timer 38 by insertion of a carrier into terminal 5 causesillumination of the lamp 46 at terminal 6 and signals the approach of acarrier toward the latter terminal so that an operator is warned againstthe insertion of a carrier into terminal 6. Similarly, operation oftimer 41 by insertion of a carrier into terminal 6 causes illuminationof lamp 45 to indicate the approach of the inserted carrier towardterminal 5. Each timer keeps the signal lamp controlled therebyilluminated for the required length of time and then breaks the lampcircuit.

In Figs. 2 and 3 is shown a modified means for operating the injectordevices 7 and 8. Here the air valves are omitted and the injection iscontrolled by opening and closing the injector ports 17. This isaccomplished by rack and gear trains which operatively connect thesolenoids 25 and 2 to the injector sleeves 15* for rotating the latter.Each solenoid has a core rod 49 provided with a rack 50. Said rackmeshes with a pinion 51 which is fixed to a gear 52 for rotating withit. The gear 52 meshes with gear teeth 53 formed upon the outwardlyprojecting end of the threaded injector sleeve 15 The solenoids arecontrolled by the switches and timers as previously described and when asolenoid is energized it draws the rod 49 inward and the rod through itsgearing with the injector sleeve 15 rotates the latter to open theinjector port 17. Connected to the rod 49 and to armed point upon therack mounting is a spring 54 which resists by tension the shifting ofthe rod by the solenoid. Consequently when the timer controlling thesolenoid breaks the circuit thereof the spring automatically retractsthe rod and causes the rotation of the injector sleeve for closing theport 17.

The degree to which the injector port of either injector device isopened by its solenoid is adjustable by means including a threaded stop55. Said 1 stop is engageable in any one of a number or threadedapertures 56 longitudinally spaced along the case rod 49 of the solenoidand is adapted to engage a fixed stop 5'7 upon the end of the solenoid.Thereby the port-opening movement of rod 49 is limited according to theposition of the stop screw 55.

Fig. 4 shows a dispatch tube apparatus similar to that of Fig. 1provided with a motor driven compressor for supplying the injectordevices with air, together with electrical means for starting saidcompressor from either terminal of the dispatch tube and causing the airto be directed from the compressor to the appropriate injector device.The outlet of the compressor 58, is connected the injector valves 22 an23 by two branch pipes 59, and the compressor is driven by an electricmotor 60. There are two timers 61 and 62 open.- ble by the terminalswitches 31 and 32 respectively. Each of said timers serves to start andcontrol the motor, while timer 61 independently controls thevalve-operating solenoid 25 timer 62 independently controls the solenoid26.

For supplying the timers with current there are two line Wires 63 and64. Wire 63 leads to timer 61, and is also connected to timer 62 througha conductor 65. A conductor 66 leads from wire 64 to the solenoid 25 andanother conductor 67 leads from said wire to solenoid 26. For supplyingcurrent to the motor there are two line wires 63 and 69. Wire 68 isconnected to a conductor 68 leading to two motor starters '70 and 71 andwire 69 is directly connected to one terminal of the motor. Anotherconductor 71 connects both motor starters and is directly connected tothe 1 other terminal of the motor. A conductor 72 connects the timer 61to motor starter and a conductor '73 connects timer 62 to motor starter'71. The solenoid 25 is connected to conductor 2 by a conductor 74 and aconductor 75 connects solenoid 26 to conductor '73. Switch 31 isconnected by a conductor 76 to the timer 61 and by a conductor 7'7 tothe motor starter 70 and the conductor 66. Similarly switch 32 isconnected by a conductor 78 to the timer 62 and by a conductor 79 to themotor starter '71 and the solenoid conductor 67. The conductors 4'7 forsignal lamp 45 lead from the solenoid conductors 67 and While theconductors 48 for signal lamp 46 lead from the solenoid conductors 66and 74.

Insertion of a carrier into terminal 5 closes switch 31 and closes thetimer circuit which includes the line wires 63 and 64 and conductors 66,77 and 76 for the operation of the timer 61. Said timer closes thecircuit of motor starter 70 which includes conductors '72, 66- and '17,and the motor circuit is" closed by the starter to start the motor anddrive the compressor. The timer also closes the circuit or" the solenoid25, which circuit includes conductors 66, 72 and '74, and the solenoidopens valve 22. Thereby, air from the compressor is admitted to theinjector device '7 for the propulsion of the inserted carrier to theterminal 6. Closure of the solenoid circuit also closes the circuit ofsignal lamp 46 which is illuminated to indicate the approach of thecarrier to terminal 6.

Insertion of a carrier into terminal 6 closes switch 32 and closes thecircuit of timer 62 which circuit includes the line wires 63 and 64 andconductors 65, 67, '79 and 78. The timer then operates the motor starter'71 through the circuit of the latter which includes the conductors 6'7,79 and 73, and the motor starter closes the motor circuit to start themotor and drive the compressor. Timer 62 also closes the circuit ofsolenoid 26 which circuit includes the conductors 73, 75 and 67. Thesolenoid then opens valve 23, valve 22 having been previously closed byits spring, and air from the compressor is admitted to in jector 8 forthe propulsion of the inserted carrier to terminal 5. Closure of thesolenoid circuit also closes the circuit of lamp 46 to indicate theapproach of the carrier to terminal 5. When either of the switches 31and 32 is operated the other is open so that only one of the timers andone of the solenoids is operated at a time. The closure of eitherswitch, however, causes the motor to operate.

What I claim is:

1. A pneumatic dispatch tube apparatus comprising a dispatch tube line;an injector device to inject air into said line and cause a flow of airfor the propulsion of a carrier in one direction along the line; anoppositely directed injector device to inject air into the line andcause a flow of air for the propulsion of a carrier in the oppositedirection along the line; and means to render said injector devicesoperative independently.

2. A pneumatic dispatch tube apparatus comprising a dispatch tube line;an injector device for injecting air into the tube line at anintermediate point in the line and causing a flow of air for thepropulsion of a carrier in one direction; and an oppostely directedinjector device for injecting air into the tube line at an intermediatepoint in the line and causing a flow of air for the propulsion of acarrier in the opposite direction along the line.

3. A pneumatic dispatch tube apparatus comprising a dispatch tube line;an injector device to inject air into said line and cause a flow of airfor the propulsion of a carrier in one direction along the line; and anoppositely directed injector device to inject air into the line andcause a flow of air for the propulsion of a carrier in the oppositedirection along the line.

4. A pneumatic dispatch tube apparatus comprising a dispatch tube line;an injector device for injecting air into the tube line at anintermediate point in the line and causing a flow of air for thepropulsion of a carrier in one direction; an oppositely directedinjector device for injecting air into the tube line at an intermediatepoint in the line and causing a flow of air for the propulsion of acarrier in the opposite direction along the line; and means to rendersaid injector devices operative independently.

5. A pneumatic dispatch tube apparatus comprising a dispatch tube lineprovided with longitudinally spaced terminals each serving for sendingand discharging carriers; an injector device for injecting air into saidtube at an intermediate point in the line and causing a flow of-air forthe propulsion of a carrier along the line in one direction; anoppositely directed injector device for injecting air into the tube lineat an intermediate point in the line for the propulsion of a carrier inthe opposite direction; means for supplying air under pressure to saidinjector devices; means to admit the air under pressure to said devicesindependently; and electric signal means to indicate at either terminalthe approach of a carrier from the opposite terminal.

6. A pneumatic dispatch tube apparatus comprising a dispatch tube line;an injector device to inject air into said line and cause a flow of airfor the propulsion of a carrier in one direction along the line; anoppositely directed injector device to inject air into the line andcause a flow or" air for the propulsion of a carrier in the oppositedirection along th line; and adjustable means for varying the injectionof air by said devices.

'7. A pneumatic dispatch tube apparatus comprising a dispatch tube line;an injector device to inject air into said line and cause a flow of airfor the propulsion of a carrier in one direction along the line; anoppositely directed injector device to inject air into the line andcause a flow of air for the propulsion of a carrier in the oppositedirection along the line; and adjustable means for varying the injectionby said devices independently.

8. A pneumatic dispatch tube apparatus comprising a dispatch tube line;an injector device to inject air into said line and cause a flow of airfor the propulsion of a carrier in one direction along the line; anoppositely directed injector device to inject air into the line andcause a flow of air for the propulsion of a carrier in the oppositedirection along the line; and means for cutting either of said injectordevices out of service.

9. A pneumatic dispatch tube apparatus comprising a dispatch tube lineopen at longitudinally spaced points for admission and discharge of air;an injector device to inject air into the said line at an intermediatepoint between said admission and di charge points in the line and causea flow of air for the propulsion of a carrier along the line in onedirection; and an injector device to inject air into the tube line at anintermediate point in the line between said admission and dischargepoints and cause a flow of air for the propulsion of a carrier in theopposite direction along the line.

10. A pneumatic dispatch tube apparatus comprising a dispatch tube lineopen at both ends for ingress and egress of air; an injector device toinject air into said line at an intermediate point in the line and causea flow of air for the propulsion of a carrier along the line in onedirection; an injector device to inject air into the tube line at anintermediate point in the line and cause a how of air for the propulsionof a carrier in the opposite direction along the line; and means torender said injector devices operative independently.

11. A pneumatic dispatch tube apparatus comprising a dispatch tube lineprovided with longitudinally spaced terminals each serving for sendingand discharging carriers; an injector device having an injector port toinject air into said line at an intermediate point in the line and causea flow of air for the propulsion of a carrier in one direction along theline; an injector device having an oppositely directed injector port toinject air into the line at an intermediate point in the line and causea fiow of air for the propulsion of a carrier in the opposite directionalong the line; elect 'ical means operable by the insertion of a carrierinto either terminal to render the appropriate injector device operativefor the propulsion of a carrier to the other terminal; iming means tocontrol the duration of operation of either injector device; means toautomatically render either injector device inoperative subject to thetiming means; and electric signal means operable by the insertion of acarrier into either terminal to indicate said insertion at the oppositeterminal.

12. A pneumatic dispatch tube apparatus com prising a dispatch tube lineprovided with terminals at longitudinally spaced stations serving forsending and discharging carriers; an injector device to inject air intosaid line at an intermediate point in the line and cause a flow of airfor the propulsion of a carrier in one direction along the line; aninjector device to inject air into the line at an intermediate point inthe line and cause a flow of air for the propulsion of a carrier in theopposite direction along the line; and electrical means operable ateither station to render the appropriate injector device operative forthe propulsion of a carrier to the other station.

13. A pneumatic dispatch tube apparatus comprising a dispatch tube lineconnecting longitudinally spaced carrier sending and dischargingstations; an injector device having an injector port disposed anddirected to inject air into said line at an intermediate point in theline and cause a flow of air for the propulsion of a carrier in onedirection along the line; means for opening and closing said port; aninjector device having an oppositely directed injector port to injectair into the line and cause a flow of air for the propulsion of acarrier in the opposite direction along the line; means for opening andclosing the latter port; and means operable at either station to openthe appropriate injector port for the propulsion of a carrier to theother station.

14. A pneumatic dispatch tube apparatus comprising a dispatch tube lineconnecting longitudinally spaced carrier sending and dischargingstations; an injector device having an injector port disposed anddirected to inject air into said line at an intermediate point in theline and cause a flow of air for the propulsion of a carrier in onedirection along the line; means for opening and closing said port; aninjector device having an oppositely directed injector port to injectair into the line and cause a how of air for the propulsion of a carrierin the opposite direction along the line; means for opening and closingthe latter port; means operable at either station to open theappropriate injector port for the propulsion of a carrier to the otherstation; and means to automatically close the opened port after apredetermined time.

15. A pneumatic dispatch tube apparatus comprising a dispatch tube lineconnecting longitudinally spaced carrier sending and dischargingstations; an injector device having an injector port disposed anddirected to inject air into said line at an intermediate point in theline and cause a flow of air for the propulsion of a carrier in onedirection along the line; means for opening and closing said port; aninjector device having an oppositely directed injector port to injectair into the line and cause a flow of air for the propulsion of acarrier in the opposite direction along the line; means for opening andclosing the latter port; and electrical means operable at either stationto open the appropriate injector port for the propulsion of a carrier tothe other station.

16. A pneumatic dispatch tube apparatus comprising a dispatch tube lineconnecting longitudinally spaced carrier sending and dischargingstations; an injector device having an injector port disposed anddirected to inject air into said line at an intermediate point in theline and. cause a iiow of air for the propulsion of a carrier in onedirection along the line; means for opening and closing said port; aninjector device having an oppositely directed injector port to injectair into the line and cause a flow of air for the propulsion of acarrier in the opposite direction along the line; means for opening andclosing the latter port; means operable at either station to open theappropriate injector port for the propulsion of a carrier to the otherstation; and adjustable means to vary the degree to which the injectorports are opened.

17. A pneumatic dispatch tube apparatus comprising a dispatch tube lineconnecting longitudinally spaced carrier sending and receiving stations;an injector device to inject air into said tube line at an intermediatepoint between said stations to cause a flow of air through said tubeline for the propulsion of a carrier in one direction along the line; aninjector device to inject air into the tube line at an intermediatepoint between said stations to cause a flow of air through the tube linefor the propulsion of a carrier in the opposite direction along theline; and means operable by the insertion of a carrier into the line ateither station to render the appropriate injector device operative.

18. A pneumatic dispatch tube apparatus comprising a dispatch. tube lineprovided with longitudinally spaced terminals each serving for sendingand discharging carriers; an injector device for injecting air into saidtube line at an intermediate point in the line and causing a flow of airfor the propulsion of a carrier along the line in one direction; anoppositely directed injector device for injecting air into the tube lineat an intermediate point in the line for the propulsion of a carrier inthe opposite direction; an air compressor havin fluid connections withsaid injectors; and means operable from either terminal to start thecompressor and direct air therefrom to the appropriate injector devicefor the propulsion of a carrier toward the other terminal.

19. A pneumatic dispatch tube apparatus comprising a dispatch tube lineprovided with longitudinally spaced terminals each serving for sendingand discharging carriers; an injector device for injecting air into saidtube line at an intermediate point in the line and causing a flow of airfor the propulsion of a carrier along the line in one direction; anoppositely directed injector device for injecting air into the tube lineat an intermediate point in the line for the propulsion of a carrier inthe opposite direction; an air compressor having fiuid connections withsaid injectors; a motor for driving said compressor; electrical meansoperable from one of the tube terminals to start the motor andcompressor and direct air from the compressor to the appropriateinjector device; electrical means operable from the other terminal tostart the motor and compressor and direct air from the compr ssor to theother injector device; and timing means to control the duration of themotor operation.

20. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving terminals spaced therealong; means for introducingcarrierpropelling air into said line at an intermediate point betweensaid terminals and directing it toward one of the terminals for carrierpropulsion thereto; valve means to control the introduction of air atsaid intermediate point; means operable at the other of said terminalsfor controlling said valve means; means to automatically hold said valveopen for a predetermined period; and spring means to automatically closesaid valve at the conclusion of said period.

21. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving terminals spaced therealong means for introducingcarrierprcpelling air into said line at an intermediate point betweensaid terminals and directing it toward one or" the terminals for carrierpropulsion thereto; valve means to control the introduction of air atsaid intermediate point; means operable at the other of said terminalsfor controlling said valve means; electrical timing means to hold saidvalve open for a predetermined period; and spring means to automaticallyclose said valve at the conclusion of said period.

22. A pneumatic dispatch tube apparatus com arising a dispatch tube linehaving terminals paced therealong means f or introducing carrierrop ngair into said line at an intermediate nt it. the line between saidterminals and diig it toward one of the terminals for carpropulsiothereto; and means operable at e other terminal to control the admissionof air the line at said intermediate point.

prising between said terminals and directing it toone or" tl e terminalsfor carrier propulsion means to control the introduction .matic dispatchtube apparatus comspaL-ch tube line having sending and ninals spacedtherealong; means for introducing c '--oropelling air into said line atan termed: te point between said terminals and directing it toward oneof said terminals for carrier propulsion hereto; means for introducingcarrier=-propelling air at an intermediate point in the line betweensaid terminals and directing it toward the other of said terminals forcarrier propulsion thereto; and means operable at either te-r iinal torender the appropriate one of said diate point in the line between saidterminals and directing it toward the other of said terminals forcarrier propulsion thereto; means operable at either terminal torenderthe appropriate one of said air introduction means operative for thepropulsion of a carrier to the other terminal; and means toautomatically rer. xer either of said air introduction means inoperativewhen the other is operative.

26. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving sending and discharge terminals spaced therealong; means forintroducing carrier-propelling air into said line at an intermediatepoint between said terminals and directing it toward one of saidterminals for carrier propulsion thereto; means for introducingcarrier-propelling air at an intermediate point in the line between saidterminals and directing it toward the other terminal for carrierpropulsion thereto; means operable at either terminal to render theappropriate one of said air introduction means operative for thepropulsion of a carrier to the other terminal; and adjustable means tovary the degree of air introduction.

2'2. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving sending and discharge terminals spaced therealong; means forintroducing carrier-propelling air into said line at an intermediatepoint between said terminals and directing it toward one of saidterminals for carrier propulsion thereto; means for introducingcarrier-propelling air at an intermediate point in the line between saidterminals and directing it toward the other of said terminals for ca'ier propulsion thereto; means operable at either terminal to render theappropriate one of said air introduction means operative for thepropulsion of a carrier to the other terminal; and adjustable means tovary the degree of air introduction by said two introducing meansindependently.

28. A pneumatic disptach tube apparatus comprising a dispatch tube linehaving carrier sending and discharge terminals spaced therealong; aninjector device to inject air into said line for propulsion of a carriertoward one of said terminals and including opposed members defining anannular injector port therebetween surrounding the carrier passage ofthe tube and opening into it, one of said members being mounted to shifttoward and from the other member to open and close the port; and meansoperable at the sending terminal to open the port.

29. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving carrier sending and discharge terminals spaced therealong; aninjector device to inject air into said line for propulsion of a carriertoward one of said terminals and including opposed members defining anannular injector port therebetween surrounding the carrier passage ofthe tube and opening into it, one of said members being mounted to shifttoward and from the other member to open and close the port; meansoperable at the sending terminal to open the port; and means toautomatically close the port.

30. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving carrier sending and discharge terminals spaced therealong; aninjector device to inject air into said line for propulsion of a carriertoward one of said terminals and including opposed members defining anannular injector port therebetween surrounding the carrier passage ofthe tube and opening into it, one of said members being mounted to shifttoward and from the other member to open and close the port; meansoperable at the sending terminal to open the port; means toautomatically maintain the port open for a predetermined period requiredfor the carrier propulsion; and means to automatically close the port atthe conclusion of said period.

31. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving carrier sending and discharge terminals spaced therealong; aninjector device to inject air into said line at an intermediate pointbetween the terminals for propulsion of a carrier toward one of saidterminals and including opposed members defining an annular injectorport therebetween surrounding the carrier passage of the line andopening into it, one of said port-forming members being rotatablerelatively to the other member, and screw means for shifting saidrotatable member toward and from the other member as it is rotated inopposite directions, to open and close the port; and means operable atthe sending terminal to cause the rotation of the rotatable port-formingmem her to open the port.

32. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving carrier sending and discharge terminals spaced therealong; aninjector device to inject air into said line at an intermediate pointbetween the terminals for propulsion of a carrier toward one of saidterminals and including opposed members defining an annular injectorport therebetween surrounding the carrier passage of the line andopening into it, one of said portforming members being rotatablerelatively to the other member, and screw means for shifting saidrotatable member toward and from the other member as it is rotated inopposite directions, to open and close the port; means operable at thesending terminal to cause the rotation of the rotatable port-formingmember to open the port; and adjustable means to vary the limit ofport-opening rotation of said rotatable member.

33. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving longitudinally spaced terminals each serving for sending anddischarging carriers; a pair of oppositely directed injector devices atintermediate points in said line between said terminals to inject airinto the line for carrier propulsion in opposite directions along theline, and each comprising opposed members defining an annular injectorport therebetween surrounding the carrier passage in the line andopening into it, one of said members being rotatable relatively to theother member, and screw means for shifting said rotatable portformingmember toward and from the other portiorming member as the rotatablemember is rotated in opposite directions to open and close the port; andmeans operable at either terminal to cause the rotation of the rotatableport-forming member of the appropriate injector device for propulsion ofa carrier toward the other terminal.

34. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving longitudinally spaced terminals each serving for sending anddischarging carriers; a pair of oppositely directed air injector devicesat intermediate points in said line between said terminals to inject airinto the line for carrier propulsion in opposite directions along theline, and each comprising opposed members defining an annular injectorport therebetween surrounding the carrier passage in the line andopening into it, one of said members being rotatable relatively to theother member, and screw means for shifting said rotatable portformingmember toward and from the other portforming member as the rotatablemember is rotated in opposite directions to open and close the port;means operable at either terminal to cause the rotation of the rotatableport-forming member of the appropriate injector device for propulsion ofa carrier toward the other terminal; and adjustable means to vary thelimit of portopening rotation of said rotatable members of the twoinjector devices independently.

35. A pneumatic dispatch tube apparatus comprising a dispatch tube linehaving sending and receiving stations spaced therealong; an injectordevice at an intermediate point on the line between said stations anddirected along the line toward one station; an injector device at anintel-mediate point on the line and directed along the line toward theother station; and means operable at each of said stations to render theappropriate injector device operative for propulsion of a carrier alongthe line by injection of ir into the line toward the receiving stationand by suction away from the sending station.

36. A pneumatic dispatch tube apparatus comprisim a dispatch tube linehaving sending and receiving stations spaced therealong; means having arestricted injector port at an intermediate point in the line betweensaid stations and directed into and along the line toward one station;injector means having a restricted injector port at an intermediatepoint in the line and directed into and along the line toward the otherstation; and means operable at each of said stations to render theappropriate injection means operative for propulsion of a carrier alongthe line by injection of air into the line toward the receiving stationand by suction away from the sending station.

JOHN T. NEEDHAM.

injector

